The invention is with respect to an apparatus for controlling the height of pressings in a press, and more specially for making pressings using powder material, the apparatus having a frame, in which a plate, supporting a tool part, is fixedly supported, while further tool parts may be moved in relation to the plate, and with a length measuring system which is made up of measuring elements fixed on the moving tool parts, and of further measuring elements, which are fixed in relation to the press and are designed for use with the first-named measuring elements.
Such forms of apparatus for controlling the height of pressings are for example specially important in the case of presses on which pressings are to be made starting with powder ceramic material. It is in fact important that such pressings have generally the same thickness so that, when the later firing operation has been completed, the pressings made from such material are as true to size as possible or, putting it differently, have the smallest possible tolerances, even although shrinkage takes place on firing.
So far measuring elements have been fixedly placed on the moving tool parts, further measuring elements, fixed to the press, being designed for working with the first-named measuring elements and being fixed to the press frame.
However in view of the great pressures taking effect in such presses stretching of the press frame necessarily takes place and the effect of such stretching will necessarily, in turn, have an effect on the readings produced by measuring with the outcome that the height of the pressings may not be truly or exactly controlled.